1. Field of the Invention
The present invention relates to novel monocarbonates and their use, as well as to a process for the preparation of compositions containing the monocarbonates. More specifically, the invention relates to monocarbonates having carbonate bond that is protected and is little decomposed, to lubricating oils having excellent lubricating property, cleaning property and electrically insulating property that can be used as gear oils for industrial use, engine oils for automobiles, gear oils for automobiles, lubricating oils for refrigerators, lubricating oils for rolling and lubricating oils for fibers, for which strict lubricating property and cleaning property have heretofore been required, and, particularly, to lubricating oils that can be best used for the refrigerators that use, as a cooling medium, ozone layer non-depleting hydrogenated fluorocarbons (HFC) such as R-134a, as well as to a process for the preparation of compositions containing monocarbonates.
2. Prior Art
Lubricating oils include gear oils for industrial applications, engine oils, lubricating oils for fibers, lubricating oils for rolling, lubricating oils for refrigerators, traction oils and the like oils.
As it has now been urged to operate industrial machinery under ever severe conditions, it has been demanded to produce gear oils for industrial use that are capable of maintaining lubricating property and cleaning property up to high temperature ranges. In a step of baking finish and a step of baking foods, in particular, higher performance is required in regard to lubricating property and cleaning property. For such applications, there have heretofore been used lubricating oils of the types of synthetic hydrocarbons, carboxylic esters and glycols.
However, the synthetic hydrocarbon oils and carboxylic ester oils are not still satisfactory in regard to lubricating property, form carbonized materials after heated for extended periods of time, and are not capable of playing the role of lubricating oils under high-temperature conditions. On the other hand, the glycol lubricating oils have a merit of forming carbonized materials in small amounts even after heated for extended periods of time but have insufficient lubricating property and strong hygroscopic property, leaving room for improvement in regard to lubricating property and hygroscopic property.
Accompanying the trend toward producing automotive engines of higher performance, furthermore, it has been urged to produce engine oils that maintain lubricating property, cleaning property and dispersing property at higher temperatures even after used for longer periods of time. If it is attempted to meet such demands by selecting additives, the additives are inevitably used in large amounts bringing about a harmful effect, i.e., sedimentation of a mayonnaise sludge. It has heretofore been attempted to use a mineral oil as a base oil together with the synthetic hydrocarbon oil or the carboxylic ester oil without, however, satisfactory results in regard to lubricating property, cleaning property and dispersing property when used at high temperatures for extended periods of time.
Unlike the lubricating oils for the automotive engines, i.e., for the four-cycle engines, on the other hand, the lubricating oils for the two-cycle engines are burned being added to the gasoline and, hence, its cleaning property is most important. Castor oils and polybutenes have heretofore been used as lubricating oils for the two-cycle engines, but their lubricating property and cleaning property are not still satisfactory.
Gear oils for automobiles and, particularly, gear oils for ATF must have small coefficients of friction and must be aged little. Therefore, there have heretofore been used a friction-reducing agent and a friction-adjusting agent. However, gear oils for automobiles containing these additives still have a problem in that their coefficients of friction change greatly with the passage of time.
So far, lubricating oils of the types of carboxylic ester and glycol have been used for the fibers satisfying, however, neither lubricating property nor cleaning property.
A lubricating oil consisting of beef tallow has long been used for the rolling. This lubricating oil features excellent lubricating property and rolling efficiency but has very poor cleaning property, making it necessary to carry out the step of cleansing the beef tallow. Moreover, a lubricating oil of the type of carboxylic ester has been used for the rolling featuring very good cleaning property but low practicability because of its poor lubricating property.
In the refrigerators in which ozone layer non-depleting hydrogenated fluorocarbons such as R-134a (CH.sub.2 F--CF.sub.3) have now been used as the coolant gas, mineral oils and alkylbenzene compounds that were used as lubricating oils are now no longer usable because they lack compatibility with the coolant gas. At present, a glycol ether lubricating oil has been developed for lubricating the refrigerators that use R-134a as the coolant gas.
U.S. Pat. No. 4,755,316 discloses a composition for compression refrigerators, comprising a tetrafluoroethane and a polyoxyalkylene glycol having a molecular weight of 300 to 2,000 and a dynamic viscosity of about 25 to 150 cst at 37.degree. C.
However, the glycol ether lubricating oils have insufficient heat stability, strong hygroscopic property and cause rubber sealing members such as of NBR to shrink and hardened.
In modern refrigerators for car air conditioners, furthermore, there has been employed a through-vane type rotary compressor featuring both reduced size and increased efficiency. The lubricating oil for the through-vane type rotary compressor must have a large viscosity from the standpoint of sealing property and wear resistance. However, compounds having a glycol ether structure are not utilizable since they exhibit poor compatibility with respect to the ozone layer non-depleting hydrogenated fluorocarbons such as R-134a, when their molecular weights are increased to exhibit increased viscosities. This problem holds not only for the ozone layer non-depleting hydrogenated fluorocarbons but also for the hydrogenated chlorofluorocarbons (HCFC) having a small ozone depletion potential and for a mixture of the hydrogenated fluorocarbons and hydrogenated chlorofluorocarbons. Examples of the hydrogenated fluorocarbons include R-152a (CHF.sub.2 --CH.sub.3), R-125 (CHF.sub.2 --CF.sub.3) and R-32 (CH.sub.2 F.sub.2) in addition to the above-mentioned R-134a. Examples of the hydrogenated chlorofluorocarbons include R-22 (CHClF.sub.2), R-123 (CHCl.sub.2 CF.sub.3) and R-124 (CHClF--CF.sub.3).
In recent years, furthermore, carboxylic ester lubricating oils called polyol ester and hindered ester have been developed for lubricating the refrigerators that use hydrogenated fluorocarbons as the coolant. However, these lubricating oils form carboxylic acid upon the hydrolysis or the thermal decomposition resulting in the occurrence of corrosion and wear of metals or copper-plating phenomenon in the refrigerators due to the carboxylic acid. Therefore, these lubricating oils bring about a problem concerning the durability of the refrigerators.
There has also been developed a polycarbonate lubricating oil for lubricating the refrigerators that use hydrogenated fluorocarbons as the coolant, involving, however, a problem in that carbonic acid gas evolves due to the thermal decomposition and hydrolysis. The carbonic acid gas is not condensed in an ordinary refrigerator system which uses the hydrogenated fluorocarbons as the coolant and is not desirable since it deteriorates the refrigeration efficiency and rises the temperature in the step of compression.
As for the traction oils, alicyclic hydrocarbons have heretofore been studied as the operation fluids for the traction drive without, however, satisfactory results with respect to traction performance and durability.